In a coding apparatus described in Patent literature 1, an input signal is first normalized by division by a normalization value. The normalization value is quantized to generate a quantization index. The normalized input signal is vector-quantized to generate the index of a representative quantization vector. The generated indexes, which are the quantization index and the index of the representative quantization vector, are output to a decoding apparatus.
The decoding apparatus decodes the quantization index to generate a normalization value. The decoding apparatus also decodes the index of the representative quantization vector to generate a decoded signal. The normalized decoded signal is multiplied by the normalization value to generate a decoded signal.